The following relates generally to wireless communications, and more specifically to transmission of uplink control information in a multi-carrier communication system.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency-division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal, or user equipment (UE), communicates with one or more base stations through transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the user equipment, and the reverse link (or uplink) refers to the communication link from the user equipment to the base stations. This communication link may be established through a single-in-single-out, multiple-in-single-out or a multiple-in-multiple-out (MIMO) system.
In LTE systems, a physical downlink shared channel (PDSCH) carries data and signaling information to the user equipment. The user equipment can request the retransmission of the data packets that were incorrectly received according to a hybrid automatic repeat request (HARQ) process. According to the HARQ process, the user equipment only requests the retransmission of those packets that could not be corrected by the forward error correction (FEC) codes at the user equipment. In response to the reception of the data, the user equipment produces a positive acknowledgment (ACK) that is indicative of the correct reception of the data, or a negative acknowledgment (NACK), which is indicative of an incorrect reception of the data. The ACK/NACK may be transmitted to the base station (or eNodeB) on either the physical uplink control channel (PUCCH) or multiplexed with the uplink data transmissions on the physical uplink shared channel (PUSCH).